Performance-Based Multiobjective Optimal Seismic Retrofit Method for a Steel Moment-Resisting Frame Considering the Life-Cycle Cost

Table 1

Performance level and damage state in terms of the interstory drift ratios.

Performance level	Damage state	Interstory drift ratios (%)
I	None	Δ<0.2
II	Slight	0.2<Δ<0.5
III	Light	0.5<Δ<0.7
IV	Moderate	0.7<Δ<1.5
V	Heavy	1.5<Δ<2.5
VI	Major	2.5<Δ<5.0
VII	Destroyed	5.0<Δ